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Activity 1: Breeding Bunnies In this activity, you will examine natural selection in a small population of wild rabbits. Evolution, on a genetic level, is a change in the frequency of alleles in a population over a period of time. Breeders of rabbits have long been familiar with a variety of genetic traits that affect the survivability of rabbits in the wild, as well as in breeding populations. One such trait is the trait for furless rabbits (naked bunnies). This trait was first discovered in England by W.E. Castle in 1933. The furless rabbit is rarely found in the wild because the cold English winters are a definite selective force against it. Note: In this lab, the dominant allele for normal fur is represented by F and the recessive allele for no fur is represented by f. Bunnies that inherit two F alleles or one F and one f allele have fur, while bunnies that inherit two f’s have no fur. Materials • Breeding Bunnies: Gene Frequency Data form (pdF) • Breeding Bunnies: Discussion Questions (pdf) • 50 red beans • 50 white beans • 1 paper bag or deep bowl • 3 dishes or containers • labels • pens BREEDING BUNNIES Procedures 1. Answer the questions on the Gene Frequency Data Sheet, fill in the hypothesis section and specific predictions based on that hypothesis. 2. Get into your assigned group and gather the needed materials to complete the lab. If you are working alone, proceed on your own. 3. The red beans represent the allele for fur, and the white beans represent the allele for no fur. The container represents the English countryside, where the rabbits randomly mate. 4. Label one dish FF for the homozygous dominant genotype. Label a second dish Ff for the heterozygous condition. Label the third dish ff for those rabbits with the homozygous recessive genotype. 5. Place the 50 red and 50 white beans (alleles) in the container and shake up (mate) the rabbits. (Please note that these frequencies have been chosen arbitrarily for this activity.) 6. Without looking at the beans, select two at a time, and record the results on the data form next to "Generation 1." For instance, if you draw one red and one white bean, place a mark in the chart under "Number of Ff individuals." Continue drawing pairs of beans and recording the results in your chart until all beans have been selected and sorted. Place the "rabbits" into the appropriate dish: FF, Ff, or ff. (Please note that the total number of individuals will be half the total number of beans because each rabbit requires two alleles – 1 from mom and 1 from dad.) 7. The ff bunnies are born furless. The cold weather kills them before they reach reproductive age, so they can't pass on their genes. Place the beans from the ff container aside before beginning the next round. 8. Count the F and f alleles (beans) that were placed in each of the "furred rabbit" dishes in the first round and record the number in the chart in the columns labeled "Number of F Alleles" and "Number of f Alleles." (This time you are really counting each bean, but don't count the alleles of the ff bunnies because they are no longer in the gene pool because these rabbits died before they could reproduce.) Total the number of F alleles and f alleles for the first generation and record this number in the column labeled "Total Number of Alleles." 9. Place the alleles of the surviving rabbits (which have grown, survived and reached reproductive age) back into the container and mate them again to get the next generation. 10. Repeat steps five through nine to obtain generations two through ten. If working as a team, make sure everyone in your group has a chance to either select the beans or record the results. 11. Determine the gene frequency of F and f for each generation and record them in the chart in the columns labeled "Gene Frequency F" and "Gene Frequency f." To find the gene frequency of F, divide the number of F by the total, and to find the gene frequency of f, divide the number of f by the total. Express results in decimal form. The sum of the frequency of F and f should equal one for each generation. 12. Record your group’s frequencies so your classmates can see them. 13. Graph your frequencies. Prepare a graph with the horizontal axis as the generation and the vertical axis as the frequency in decimals. Plot all frequencies on one graph. First, plot your own data. Use a solid line for F and a dashed line for f. Then, plot the class totals. Use the same symbols for each group but a different color. 14. Complete the Discussion Questions form with your group. 15. Each student will turn in a Gene Frequency Data Sheet, two graphs: 1) group data and 2) the class data, and the answers to the discussion questions. Name: __________________________________ Date:_________________ Period:____ Breeding Bunnies: Gene Frequency Data How does natural selection affect gene frequency over several generations? Come up with a hypothesis about what will happen with the breeding bunnies with fur and the naked bunnies? Write what you would predict (if your hypothesis is true, then….) about the frequency of F alleles and f alleles in the population of rabbits after 10 generations, where ff bunnies are selected against. Generation Number of FF Individuals Number of Ff Individuals Number of ff Individuals Number of F Alleles Number of f Alleles Total Alleles Gene Freq. of F 1 2 3 4 5 6 7 8 9 10 Adapted from PBS www.pbs.org/wgbh/evolution/educators/lessons/lesson4/act1.html Gene Freq. of f NAME: YOUR PARTNER’S NAMES: BREEDING BUNNIES: DISCUSSION QUESTIONS 1. What was your original hypothesis? 2. Based on your lab data, do you need to change your hypothesis? Explain. 3. Compare the number of alleles for the dominant characteristics with the number of alleles for the recessive characteristic 4. Compare the frequencies of the dominant allele to the frequencies of the recessive allele. 5. In a real rabbit habitat new animals often come into the habitat (Immigrate), and others leave the area (emigrate). How might emigration and immigration affect the gene frequency of F and f in this population of rabbits? How might you simulate this effect if you were to repeat this activity? 6. How do your results compare with the class data? If significantly different, why are they different? 7. How are the results of this simulation an example of evolution?